Development and psychometric validation of a novel scale for measuring 'psychedelic preparedness'

Abstract

Preparing participants for psychedelic experiences is crucial for ensuring these experiences are safe and, potentially beneficial. However, there is currently no validated measure to assess the extent to which participants are well-prepared for such experiences. Our study aimed to address this gap by developing, validating, and testing the Psychedelic Preparedness Scale (PPS). Using a novel iterative Delphi-focus group methodology ('DelFo'), followed by qualitative pre-test interviews, we incorporated the perspectives of expert clinicians/researchers and of psychedelic users to generate items for the scale. Psychometric validation of the PPS was carried out in two large online samples of psychedelic users (N = 516; N = 716), and the scale was also administered to a group of participants before and after a 5-7-day psilocybin retreat (N = 46). Exploratory and confirmatory factor analysis identified four factors from the 20-item PPS: Knowledge-Expectations, Intention-Preparation, Psychophysical-Readiness, and Support-Planning. The PPS demonstrated excellent reliability (ω = 0.954) and evidence supporting convergent, divergent and discriminant validity was also obtained. Significant differences between those scoring high and low (on psychedelic preparedness) before the psychedelic experience were found on measures of mental health/wellbeing outcomes assessed after the experience, suggesting that the scale has predictive utility. By prospectively measuring modifiable pre-treatment preparatory behaviours and attitudes using the PPS, it may be possible to determine whether a participant has generated the appropriate mental 'set' and is therefore likely to benefit from a psychedelic experience, or at least, less likely to be harmed.

Figure 1

The ‘DelFo Method’. Flow diagram illustrating our integration of Delphi Method with focus group discussions. The number of items evaluated in each iterative Delphi round is indicated in the diamonds.

Figure 2

Structural representation of PPS Model 1. CFA Confirmatory factor analysis model with standardised loadings. Included in the model (N = 718) were 20 items of the PPS which fulfilled loading criteria during exploratory factor analyses in a different sample (N = 518). Circles represent latent variables, squares represent observed indicators, one-way arrows represent paths and two-way arrows represent covariances.

Figure 3

Test–retest reliability Bland–Altman plot. Intraindividual differences (n = 296) between mean PPS scores for test–retest, plotted against the average of the two scores. The central line represents the mean difference, and the top and bottom lines display the 95% confidence interval.

Figure 4

Retrospective PPS predicts quality of experience and therapeutic outcomes. Panel (a) shows scatter plots illustrating the correlation between total PPS scores and MEQ (r = 0.55, p < 0.001), CEQ (r = − 0.42, p < 0.001), EBI (r = 0.43, p < 0.001), PPGI (r = 0.51, p < 0.001), COES (r = 0.57, p < 0.001) and SWEBWBS (r = 0.59, p < 0.001). Panel (b) displays violin plots for group differences between high and low preparation groups for all six outcomes. The high preparation group scored significantly higher on the MEQ (t(1234) = 14.654, p ≤0.001, EBI (t(1234) = 11.945, p ≤ 0.001), PPGI (t(1234) = 14.437, p ≤ 0.001), COES (t(1234) = 17.235, p ≤ 0.001), and SWEBWBS (t(1234) = 16.663, p ≤ 0.001), and lower scores on the CEQ (t(972) = − 8.647, p ≤ 0.001) than the low preparation group.

Figure 5

Prospective PPS predicts quality of experience and therapeutic outcomes. Panel (a) displays scatter plots illustrating the correlations between total PPS scores and global-ASC (r = 0.56, p < 0.001), and changes in the DASS subscales (depression: r =  − 0.45, p = 0.002; anxiety: r =  − 0.53, p < 0.001; stress: r =  − 0.56, p < 0.001). Panel (b) shows violin displays violin plots for group differences between high and low preparation groups for all four outcomes. The high preparation group scored significantly higher on the global-ASC (t(44) = 2.106, p = 0.041), and had significantly greater reductions in Depression (t(44) =  − 3.526, p =  < 0.001, Anxiety (t(44) =  − 3.202, p = 0.003), and Stress (t(44) =  − 3.162, p = 0.003) scores, than the low preparation group.